Comment on: “Neuropsychiatric Presentations of Common Dementia Syndromes: A Concise Review for Primary Care Team Members”

Abstract

Bell et al. [1] provide a highly insightful and clinically useful overview of the behavioral presentation of four types of dementia (i.e., Alzheimer's disease (AD), behavioral variant frontotemporal dementia (bvFTD), dementia with Lewy bodies (DLB) and vascular dementia (VaD), that are often encountered in both memory clinics and by primary care providers. In their article, they stress the importance of timely recognition of neuropsychiatric symptoms (NPS) as potential early markers of neurodegeneration and explain symptoms such as social inappropriateness, lack of motivation, and impulsivity to be part of the construct of mild behavioral impairment (MBI), analogous to mild cognitive impairment (MCI), which can precede cognitive symptoms [2]. However, in our opinion, an important concept related to NPS and MBI is missing, namely social cognition. Social cognition, first added as a core neurocognitive domain in the fifth edition of the Diagnostic and Statistical Manual for Mental Disorders (DSM-5) [3], refers to the processing and understanding of socially relevant information, necessary for adequately regulating behavior in a social interpersonal context [4]. Socio-cognitive processes include empathy, emotion recognition, and mentalizing about others' thoughts, beliefs, and feelings, which is also being referred to as Theory of Mind (ToM)) [4]. Consequently, impairments in social cognition are often at the root of behaviors such as social inappropriateness, aggression, lack of motivation, and impulsivity, that are referred to as NPS and are described as being part of MBI.

Ample evidence already exists of impaired social cognition in patients with neurodegenerative diseases [5], and particularly in patients with bvFTD, impaired social cognition is a core feature [6]. In addition to the clear descriptions by Bell et al. [1] of typical behavioral symptoms in four often encountered types of dementia (i.e., bvFTD, AD, VaD and LBD), we would like to describe the most common changes in social cognition in these dementia types, to enhance their early recognition in primary care settings. Furthermore, we give suggestions for follow up analysis in a memory clinic.

As previously mentioned, in patients with bvFTD, impaired social cognition is a core feature [6], with early symptoms of loss of empathy and impairments in both emotion recognition and in mentalizing/ToM. In patients with AD, social cognitive functions are also known to be impaired, including emotion recognition and ToM, albeit to a lesser extent than in patients with bvFTD [7]. Particularly in young onset AD, social behavioral symptoms can be prevalent from an early phase on, which led to the definition of a behavioral subtype of AD [8]. Up until now, in patients with VaD and LBD, less is known about social cognitive functioning in an early disease stage, but preliminary results suggest impairments in ToM and emotion recognition in both types of dementia [5, 7].

As Bell et al. [1] propose, access to and training with objective clinical tools that are sensitive to early changes in behavior is crucial for primary care providers, and they report that the MBI Checklist (MBI-C) and Neuropsychiatric inventory (NPI) are useful objective measures to achieve this goal. Although these instruments are useful and important in our opinion, they remain subjective information sources (e.g., informant or clinician informed), and do not replace objective measures. Through extensive research in a broad range of clinical and non-clinical populations, a wide array of validated neuropsychological test instruments has emerged to objectively measure aspects of social cognition, including emotion recognition and mentalizing/ToM (e.g., with the Ekman 60 Faces Test (EFT), the Reading the Mind in the Eyes Test (RMET), and The Awareness of Social Inference Test (TASIT)) [9]. Performances on social cognition tests have known associations with measures of independent daily living and experienced well-being, and performances cannot solely be explained by the (lack of) integrity of other neurocognitive functions, including memory, attention, and processing speed [7, 9].

In conclusion, in addition to the assessment of behavioral symptoms (e.g., with the NPI and MBI-C) and neurocognitive domains such as memory and language, we deem social cognition a crucial domain to assess in order to enhance the recognition of often encountered types of dementia. A practical guideline for stepped diagnosis and care could be to assess NPS and MBI due to potential underlying neurodegeneration with the NPI and MBI-C in the primary care setting, after which referral to the memory clinic can be considered for specialized assessment of social cognitive functioning with neuropsychological tests.

Conception and design of this letter were performed by F.S., as well as writing the first draft and revising the final draft; M.E.S., R.B.H., E.v.d.B., B.C.v.M., and J.M.S. reviewed the work critically for intellectual content and approved the final draft.

The authors have nothing to report.

The authors declare no conflicts of interest.

This publication is linked to a related reply by Bell et al. To view this article, visit https://doi.org/10.1111/jgs.19413.